Coin identifying circuit



United States Patent COIN IDENTIFYING CIRCUIT Alfred H. Faulkner,Chicago, and Robert L. Hulfman, Palatine, 111., assignors to GeneralTelephone Laboratories, Incorporated, a corporation of DelawareApplication February 18, 1954, Serial No. 411,209

11 Claims. (Cl. 179-63) This invention relates in general to anarrangement for identifying the value of a coin deposited in a coinreceiving means and more particularly to an arrangement comprising anelectronic tone generator to be used with a telephone paystation andcontrolled by a switch arrangement in the coin receiving means for thepurpose of generating electrical pulsations, dependent on the value of acoin deposited at the paystation, to thereby enable the coin to beidentified.

The usual practice today for identifying coins deposited in a telephonepaystation is to have a number of gongs arranged along the coin chutesso that when a nickel is deposited one of the gongs is struck once; whena dime is deposited the same gong is struck twice and when a quarter isdeposited another gong is struck once. An arrangement of this type isshown in a Patent No. 2,235,648, issued to Shaun, March 18, 1941,wherein a coin transmitter is arranged in close proximity to the gongsand picks up the vibrations produced by the struck gong and transmitscorresponding electrical pulsations over the line so that an operatormay identify the coin according to the tone produced in her telephoneset by the electrical pulsations. The gong which is arranged to bestruck by a nickel or dime vibrates at one particular frequency so thatthe operator identifies a nickel bythe fact that she hears one tone ofthe particular frequency transmitted over the coin transmitter andidentifies the dime by hearing the same frequency twice in quicksuccession whereas the quarter gong gives rise to a vibration of anotherfrequency which is transmitted by the coin transmitter to be heard bythe operator and identified by her as a quarter. This arrangement givesrise to two important difficulties in that the coin transmitter providesan undesirable impedance in the line circuit and secondly the secondstroke of the dime against its gong is difficult to distinguish from thefirst stroke as the gong may be still vibrating.

The present invention eliminates these problems by providing, in placeof the gongs and coin transmitter, lever controlled switches operated bythe coins to control a transistor oscillator for the purpose ofproducing an identifiable audio frequency on the line. A nickel onfalling through the chute strikes one lever to control the oscillatoraccordingly. The dime strikes another lever and the first lever tocontrol the oscillator for the purpose of producing two separatesplashes of identifiable tones of the same frequency as the nickel. Thequarter on deposit strikes a third lever for controlling the oscillatorto produce a tone of another frequency to enable the operator toidentify the quarter. The transistor oscillator as shown in oneembodiment is shunted from the line except for a short period when acoin is deposited and therefore it provides no impedance to the linewhile connections are being established or during conversation. Theoscillator avoids the problem of providing two distinct tones from avibrating gong as it generaes tones onlyduring a short interval that thevarious levers are activated by their respective coins to close theirassociated switches or contacts. One modification of the presentinvention shown herein utilizes a transistor oscillator circuit normallyincomplete and connected to one side of the line at all times so thateven when completed and operative practically no impedance to the lineis presented.

Present paystation practice generally allows completion of a local callwithout intervention by an operator, and only on toll calls is operatorcontrol utilized. How ever, no distinction will be made between localand toll calls or postpay and prepay paystations as these factors are ofno consequence in the present invention and the calling party may beconsidered in the present invention as completing all calls with the aidof an operator on reaching any well-known type of combined linerecording trunk after dialling a preliminary digit over any well knowntype of finder-selector link.

Fig. 1 is a schematic diagram of a standard type of coin chute such asshown in the aforementioned patent modified by replacing the gongsadapted to be struck by.

and circuit arrangement as shown in Fig. 1 with the exception that anadditional lead is provided which is grounded in the line circuit andone spring may be omitted from those controlled by nickels and dimes.Similar parts are designated by a primed number.

Assuming now that a calling party at a paystation such as in Fig. 1 hasproceeded to reach combined line recording trunk 25 over finder-selectorlink 24 on dialling of a preliminary digit and on conversing with theoperator has been requested to deposit forty-cents in the coin receivingmechanism. At this time a circuit is completed from battery at thecombined line recording trunk 25, over finder-selector link 24,subscribers line circuit 23, the -L line, dial springs 26, hookswitchsprings 27, coil 28, transmitter 29, springs 21, 17, 19 and 9, over the+L line, back over line circuit 23, link 24 and trunk 25 to ground.Resistor 30 is normally short circuited and is in the line only whensprings 19 and 9 or 21 and 17 are open so that at most only an impedanceof ohms is added to the line and that only for an instant while a coinis deposited. Levers 5, 6 and 7 are balanced on their pivots 5b, 8 and16 respectively so that their respective coin pads 5a, 6a and 7anormally rest against the edges of their respective channel formingmembers adjacent their respective channel openings. Each lever isprevented from rotation until its pad is struck by a coin at which timethe associated lever is moved. away from its associated channel. Thecoin pads are attached to the coin levers for the purpose of providing alarge surface to be struck by a coin as the levers themselves are wires,which do not provide sufficient surface to be sure that a coin inrolling through its channel will strike the lever more than a glancingblow.

The calling party deposits a nickel which on dropping through the coinchute strikes pad 6a causing lever 6 to rotate about pivot 8 and closesprings 9 and 10 and open springs 9 and 19 to remove the shunt fromresistor 30 and include it in the line. As 150 ohm resistor 30 is notnow shunted from the line a drop in voltage occurs across it to bias thecollector 14 with respect to the base circuit and cause collectorcurrent to flow. As

collector current flows, the base is made negative with respect to theemitter l3 and the emitter circuit begins 2,856,460 Patented Oct. 14,1958 to draw current, thereby increasing the flow of current in thecollector circuit to in turn increase current how in the emitter circuituntil a saturation point in collector current flow is reached, afterwhich both the collector and emitter current fall rapidly away. The .2mf. condenser 11 which is charged during the period that the emittercurrent was increasing now discharges through the 10,000 ohm resistor12. The current passing through bias resistor 30 is of course increasingand decreasing in the same time sequence to provide a correspondingvoltage fluctuation in the line. After condenser 11 discharges,collector current again flows to repeat the process. Thus the currentpassing through resistor '30 is periodically varied at an audiofrequency rate to provide a tone signal to the operator. Reference maybe made to pages 289, 290, Figs. 7b and 8 on pages 318 and 319respectively and Fig. 1 on page 433 of the publication The Transistor,by Bell Telephone Laboratories, for a more complete explanation of thetransistor oscillator. A type 1692 Western Electric transistor may beused in the present invention while the base circuit resistor 31 may bebetween 2,000 and 10,000 ohms dependent on the characteristics of theparticular transistor.

As lever 6 is returned quickly to normal after the nickel has struck it,springs 9 and 10 open to terminate operation of the transistoroscillator immediately and thus interfering vibrations in the event ofanother coin deposit are prevented, as oscillations caused by the firstdeposit cease before the second deposit is made. Pad 6a on striking theedges of the channel forming members prevents lever 6 from oscillatingon its pivot to again cause springs 9 and 10 to close and only onedistinct tone is all that can be provided. Resistor 30 is again shuntedfrom the line when springs 9 and 19 close.

A dime on deposit in the chute strikes pad a to rotate lever 5 aboutpivot 5b to close springs 9 and and to complete the same circuit forcausing the transis'tor oscillator to provide a tone of the samefrequency and in the same manner as previously described when the nickelstruck lever 6. Lever 5 is prevented from oscillat'ing about 511 whenpad 5a strikes the edges of its respective channel forming members sothat springs 9 and 10 are closed only once for a short interval whenlever 5 is rotated by the dime. The dime travels on down the chute andstrikes pad 6a to rotate lever 6 by which time all oscillationsgenerated by the transistor oscillator caused by operation of lever 5have ceased, and a dist'inct tone is produced by the transistor in thesame manner as previously described when the nickel rotated lever 6.

A quarter on deposit in the chute strikes pad 701 to rotate lever 7about pivot 16 to open the shunt around bias resistor 30 at springs 21and 17 so that the aforedescribed operations take place except, that assprings 18 and 17 are closed, the discharge circuit for condenser 11 isthrough the 10,000 ohm and 100,000 ohm resistors 12 and 20 respectively.The constants of this oscillator circuit are diiferent from thatpreviously described as the 100,000 ohm resistor 20 is now in thedischarge circuit and therefore a tone of a different frequency fromthat generated before is now generated so that the operator may identifythe depo ited coin as a quarter. Lever 7 returns to normal as the coincontinues to fall and is prevented from further rotation by pad 7a in amanner similar to that described.

The values of the resistors 12 and 20 may each be varied between 10,000and 100,000 ohms to provide suitable tones of audio frequency andresistor 31 may be varied within the range of 2,000 to 10,000 ohms asbefore described dependent on the transistor used.

The modification shown in Fig. In of the present invention provides anormally open circuited transistor oscillator which is in shunt with theline only when a coin is deposited and therefore draws very little linecurrent even during the period when utilized. An additional lead 33shown grounded in the subscribers line circuit is provided, however, theprovision of such a lead is often standard practice for the purpose ofsecuring additional control functions. Such a ground may be furnishedfrom equipment other than the line circuit.

The operation of the coin levers is similar to that previously describedwith the exception that as a shunt around the transistor circuit neednot be opened when a coin is deposited spring 19 is omitted and spring21 is used for a difierent purpose. The transistor circuit is opencircuited unless a coin is deposited, at which time, either springs 9'and 10' are closed and opened twice in rapid succession if a dime isdeposited, once if a nickel is deposited or springs 17' and 18' areclosed and opened once if a quarter is deposited.

Closure of springs 9' and 10 completes a circuit from one side of theline through collector 14, resistor 31', springs 9 and 10 to ground inthe subscribers line circuit over lead 33 so that the collector beginsto draw current. The emitter 13 also begins to draw current and aftersaturation is reached condenser 11' discharges through resistor 12 andsprings 17' and 21' which short resistor 20' to enable the collector toagain draw current. Thus the collector current is varied in a mannersimilar to that already described. As the collector current varies, thecurrent in the line is varied accordingly at an audio frequency rate toprovide a corresponding tone signal during the short period of timesprings 9' and 10 are closed.

When springs 17 and 18 are closed on deposit of a quarter the sameprocedure takes place with the exception that as springs 17' and 21' areopen and springs 17 and 18' closed the collector circuit is completedthrough these latter springs instead of springs 9 and 10' and condenser11 discharges through resistors 12 and 20'. The collector current andtherefore the line current is therefore varied at a different audiofrequency rate than before and thereby a different tone signal isprovided.

In the described modification of the present invert tion it is preferredthat resistor 20' be 27,000 ohrns; resistor 12' be 47,000 ohms, resistor31 be 47,000 ohms and condenser 11 be .22 Inf.

The foregoing is a description of one embodiment of our invention andone modification thereof in a form suitable for use with a telephonepaystation, however we do not wish to limit ourselves thereto and haveset forth in the appended claims the structure that we think encompassesthe invention.

What is claimed is:

1. In a telephone system utilizing a line for establishing a call andhaving a coin receiving means including a coin controlled means, saidlast means controlled in accordance with the denomination of a coindeposited in said receiving means, an oscillator circuit, saidoscillator circuit shunted from said line by said last means so as tonormally provide no impedance to said line, said last means controlledon deposit of a coin to remove said shunt and cause said oscillator toprovide electrical pulsations in said line corresponding to thedenomination of a coin deposited in said receiving means.

2. In a telephone system, a line having a coin receiving meansassociated therewith and a coin controlled switch operated a number oftimes corresponding to the denomination of a coin deposited in saidmeans, a tone generator associated with said line through contacts ofsaid switch so that said generator is normally inoperative, operation ofsaid switch by one coin of one denomination deposited in said receivingmeans rendering said generator operative and causing it to apply a tonefrequency to said line for one particular time period only, operation ofsaid switch by a coin of another denomination deposited in saidreceiving means rendering said generator operative a plurality of timeperiods and causing it to apply a tone frequency during each of saidplurality of periods to said line.

3. In a telephone paystation having chutes for receiving deposited coinsof different denomination, a switch adjacent said coin chutes, saidswitch arranged to be operated once by a deposited coin of onedenomination and arranged to be operated successively by a coin ofanother denomination, atransistor oscillator associated with saidswitch, and means controlled by said switch for causing said oscillatorto generate a tone of one frequency for one time period for eachoperation thereof whereby a coin of one denomination is identified bysaid tone for one time period and a coin of said other denomination isidentified by successive tones.

4. In a telephone system of the type having a station associated with aline over which a connection and a talking circuit to a central officemay be established and wherein a coin receiving means is provided atsaid station, the improvement comprising a switch having several sets ofcontacts arranged to be operated by a coin deposited in said coin chute,and an oscillator connected to said line through one set of contacts ofsaid switch so as to be normally inoperative and connected to said linethrough another set of contacts of said switch so as to provideelectrical oscillations to said line conforming to the deposited coinfor the purpose of enabling said coin to be identified.

5. In a telephone system of the type having a .station associated with aline over which a connection and a talking circuit to a central officemay be established and wherein a coin receiving means is provided atsaid station, the improvement comprising an oscillator connected to saidline and normally ineffective to provide electrical oscillations to saidline, a switch, .a pair of arms associated with said coin receivingmeans whereby one of said arms is operated by a coin of one denominationdeposited in said receiving means to operate said switch and said onearm and the other arm are arranged to be operated successively on thedeposit of a coin of another denomination deposited in said receivingmeans to operate said switch successively, the contacts of said switcharranged when operated by a deposited coin to connect said oscillator tosaid line so as to render said oscillator effective to provide a burstof electrical oscillations of a particular frequency to said linewhereby a coin of one denomination may be identified and whereby a coinof said other denomination may be identified by the successive bursts ofelectrical oscillations provided to said line.

6. A combination for use with a coin receiving means adapted to receivecoins of different denominations comprising a control means operated inaccordance with the denomination of a coin deposited in said receivingmeans, and an oscillator circuit normally ineffective to provideelectrical pulsations and controlled by said control means on operationthereof by a deposited coin of one denomination to provide one group ofelectrical pulsations of one of two audible frequencies dependent uponthe denomination of the deposited coin and controlled by said controlmeans on operation thereof by a deposited coin of another denominationto provide successive groups of said pulsations of one frequency.

7. An arrangement such as claimed in claim 6, in which said oscillatorcircuit comprises a transistor, a plurality of circuits eachindividually corresponding to different coin denominations and eachcontrolled in response to the de posit of a coin of its individuallycorresponding denomination to control said transistor accordingly.

8. An arrangement claimed such as claimed in claim 6 in which saidcontrol means comprises a plurality of coin controlled switches eachcontrolled in accordance with the denomination of a coin deposited insaid receiving means.

9. An arrangement such as claimed in claim 6, in which said controlmeans comprises a switch having contacts, and means for closing saidcontacts once for rendering said oscillator effective to provide saidone group of electrical pulsations on deposit of a coin of said onedenomination and for closing said contacts twice for rendering saidoscillator effective to provide successive groups of said electricalpulsations on deposit of a coin of said other denomination.

10. In an arrangement such as claimed in claim 6, means responsive tothe deposit of a coin of a predetermined denomination for controllingsaid oscillator to provide a group of electrical pulsations of the otheraudible frequency.

11. A combination adapted for use in a telephone system having apaystation with a coin receiving means adapted to receive coins ofdifferent denomination and wherein a talking circuit is completed fromsaid paystation to a central office over a pair of line conductors oninitiation of a call comprising an oscillator circuit, and meanscontrolled in accordance with the denomination'of a coin deposited insaid receiving means for connecting said oscillator to said line in aparticular manner for a discrete time interval dependent on thedenomination of a coin deposited in said receiving means so as to supplyelectrical oscillations to said line only during the time interval.

References Cited in the file of this patent UNITED STATES PATENTS1,792,651 Mathias Feb. 17, 1931 2,782,259 Dimond Feb. 19, 1957

